The proposed project represents the continuation of a long-standing collaboration that has enabled the development and testing of improved methods for assessing cardiovascular autonomic function across sleepwake states in polysomnographic studies. Having found in the current funding cycle that there is a significant association between autonomic dysfunction and impaired glucose metabolism, the overall goal of the proposed study is to determine whether specific noninvasive measures of autonomic function, coupled with information about current status of glucose metabolism, are capable of predicting the progression of metabolic dysfunction.